Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/04—Homopolymers or copolymers of esters
  • C09D133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S525/00—Synthetic resins or natural rubbers -- part of the class 520 series
  • Y10S525/934—Powdered coating composition

Definitions

• the invention is relating to curable powder coating compositions, and to copolymers of ethylenically unsaturated monomers to be used therein.
• the invention is relating to curable powder coating compositions, comprising an epoxy groups containing copolymer and an acid polyester.
• Curable powder compositions are known from e.g. EP-A-0773268; EP-A-0728163; U.S. Pat. No. 5,625,028, and Technical Bulletin of Shell Chemicals “VEOVA mass polymer for outdoor durable powder coatings” August 1991, VM 5.1.
• EP-A-0773268 describes acid epoxy curing type powder coating compositions, which comprised
• alkyl methacrylate As monomers (b) were exemplified inter alia alkyl methacrylate, wherein alkyl represented methyl, butyl, ethyl, isobutyl, 2-ethylhexyl, lauryl, stearyl, and/or styrene and/or dialkyl esters of unsaturated dibasic acid.
• the polymerization was actually carried out in an organic solvent like xylene and in the presence of a peroxide radical polymerization catalyst.
• a component (B) decanedicarboxylic acid was mentioned.
• EP-A-0728163 discloses powder coating compositions comprising a solid, particulate mixture of
• said epoxy functional copolymer containing from 3.0 to 5.9 moles of glycidyl groups per kilogram of epoxy functional copolymer;
• the ratio of epoxy functionality is 1:0.8 to 1, and wherein the powder coating composition has a melt viscosity of less than 5 Pa.s.
• the copolymerizable ethylenically monomer (ii) is selected from the group consisting of alkyl acrylates, alkyl methacrylates containing from 1 to 20 carbon atoms in the alkyl group, vinyl aromatic compounds and vinyl aliphatic compounds.
• the comonomer (ii) is preferably isobornyl methacrylate.
• (co)monomer component (iii) can be used a copolymerizable ethylenically unsaturated monomer different from (i) and (ii) and which is more preferably ⁇ -methylstyrene dimer.
• thermosetting resin compositions which provide coatings that allegedly possessed attractive weathering properties.
• the compositions comprised a semicrystalline polyester, consisting essentially of diol and/or triol residues and dicarboxylic acid residues.
• the diol residues had been selected from the group consisting of residues of 1,4-butanediol and 1,6-hexanediol, and the carboxylic acid residues were consisting essentially of residues of 1,4-cyclohexanedicarboxylic acid wherein at least 70% of said residues of 1,4-cyclohexanedicarboxylic acid are in trans form.
• the polyesters had an acid number of from 30 to 100 and an inherent viscosity of from 0.1 to 0.5 dl/g measured at 25° C. in a 60/40% by weight mixture of phenol/tetrachloroethane at a concentration of 0.5 g/dl.
• VEOVA mass polymer for outdoor durable powder coatings reprinted August 1991, VM 5.1 a mass copolymer LR-259 was prepared from inter alia VEOVA 10 vinyl ester monomer, styrene, methyl methacrylate, dimethyl maleate, and glycidyl methacrylate with Trigonox B (di-tert-butyl peroxide).
• copolymers were combined with a carboxyl-functional polyester as curing agent, prepared from hexanediol and decane dicarboxylic acid in a molar ratio of 1 mole of hexanediol per 2 moles decane dicarboxylic acid, under nitrogen purge and in reflux/azeotropic distillation equipment, using toluene as solvent, at a temperature in the range from 130 to 200° C., in the presence of stannous octoate as catalyst and distillation of water and toluene.
• the polyester resin showed an acid content of 207 mg KOH/g.
• curable resin compositions which provide an improved combination of physical properties of the cured coating films derived therefrom and meet the requirements from the industrial coating industry in the near future.
• coating compositions which preferably can be cured at low temperatures, i.e. in the range of from 120 to 140° C.
• Physical properties of the cured coating films which have to be improved and/or better balanced in the final combination, are inter alia: acid resistance, transparency, colouring resistance during baking, weathering resistance, mar resistance and sealer cracking resistance.
• curable resin compositions providing cured coating films having improved individual properties and/or improved combinations, as specified hereinbefore.
• Another object of the present invention is to provide a process for the preparation of a copolymer component to be incorporated into said curable resin compositions.
• a curable powder coating composition comprising at least:
• aiii) from 10 to 45 wt % of a phenylalkylene monomer having from 8 to 12 carbon atoms and preferably 8 carbon atoms;
• the molar ratio between the acid groups and epoxy groups is in the
• Suitable monomers to be used as component ai) can be selected from e.g. dimethyl maleate, diethyl maleate, di-n-propyl maleate, di-n-butyl maleate, di-isopropyl maleate, dimethyl itaconate, diethyl itaconate, di-n-propyl itaconate, di-n-butyl itaconate, di-isopropyl itaconate, di-isobutyl itaconate, and the like.
• Preferred monomers ai) are dimethyl maleate or diethyl maleate, of which dimethyl maleate is most preferred.
• Suitable monomers to be used as component aii) can be selected from e.g. glycidyl methacrylate, glycidyl acrylate, glycidyl crotonate, glycidyl cinnamate, and the like. Glycidyl methacrylate or glycidyl acrylate are most preferred.
• Suitable monomers to be used as component aiii) can be selected from e.g. styrene, vinyltoluene, dimethylstyrene, ⁇ -methylstyrene and the like. Styrene is the most preferred monomer.
• Monomers to be used as component aiv) are preferably commercially available as mixtures of alkenyl esters of branched tertiary carboxylic acids, containing each 9 carbons in the acid moiety, such as VEOVA 9 (VEOVA is a trademark of Shell for vinyl esters of VERSATIC acids, having 9 carbon atoms in their acid moiety (VERSATIC is a trademark)).
• VEOVA 9 VEOVA is a trademark of Shell for vinyl esters of VERSATIC acids, having 9 carbon atoms in their acid moiety (VERSATIC is a trademark)).
• component aiv) also mixtures of vinyl esters of branched tertiary carboxylic acids, having 9 carbon atoms in their acid residue, as major component (i.e. occurring in amounts of at least 80 wt % relative to the total weight of the component aiv) and preferably at least 90 wt %), and of vinyl esters of branched tertiary carboxylic acids, having a number of carbon atoms in their acid moiety other than 9, as minor component ( ⁇ 20 wt % and preferably ⁇ 10 wt %), can be successfully applied in the powder coating compositions of the present invention.
• Examples of said optional minor components aiv) are VEOVA 5, VEOVA 10 or VEOVA 11 esters of VERSATIC acids, having 5, 10 and 11 carbon atoms in their acid moiety respectively.
• VEOVA 9 vinylesters will be applied as sole comonomer aiv).
• Suitable monomers to be used as component av) can be selected from e.g. methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl-hexyl acrylate, isobornyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, ethylhexyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, methyl crotonate, ethyl crotonate, n-propyl crotonate, isopropyl crotonate, isobutyl crot
• the more preferred monomers av) are methyl methacrylate, methyl acrylate, isobornyl acrylate or isobornyl methacrylate, and the most preferred is methyl methacrylate.
• Preferred proportions of component ai) are in the range of from 6 to 9 wt %.
• Preferred proportions of component aii) are in the range of from 17 to 45 wt %.
• Preferred proportions of component aiii) are in the range of from 20 to 43 wt %.
• Preferred proportions of component aiv) are in the range of from 10 to 30 wt %.
• Preferred proportions of component av) are in the range of from 0 to 30 wt %.
• Suitable diacids to be used as components bi) and for the preparation of the polyester component bii) can be selected from 1,2-cyclohexanedicarboxylic acid (hexahydrophthalic acid), 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetradecanedioic acid, succinic acid, glutaric acid, adipic acid, malonic acid, azelaic acid, pimelic acid, suberic acid, dodecanedioic acid, sebacic acid, their anhydrides, nadic methyl anhydride and mixtures thereof, or anhydrides thereof.
• Dodecanedioic acid and 1,2-cyclohexanedicarboxylic anhydride are the preferred acids.
• the polyhydric alcohol component for the polyesters bii) can be suitably selected from e.g. ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, 1,4-cyclohexane-dimethanol, 1,4-cyclohexane diol, neopentyl glycol, hydroxypivalate, trimethylolpropane, di(trimethylo-propane), hydrogenated bisphenol A, hydrogenated bisphenol F, pentaerythritol, and mixtures thereof.
• Branched polyhydroalkanes such as di(
• polyester bii di-trimethylolpropane and hexahydrophthalic anhydride are most preferred.
• a polyester bii is applied, which has been derived from 0.2 to 0.3 moles di-trimethylol propane per mol hexahydrophthalic anhydride, and having an acid value of from 4600 to 4900 mmol/kg.
• powder coating compositions copolymer components (a) are to be included, which show an epoxy group content in the range of from 1000 to 4000 meq/kg and preferably from 2000 to 3000 meq/kg.
• the weight average molecular weight of the copolymer (a) components is in the range of from 2000 to 10.000 and preferably from 4000 to 7000.
• the copolymer components (a) are prepared by mass (or bulk) polymerization, i.e. without any solvent of the components ai) through av) at a temperature in the range of from 155 to 180° C., and in the presence of a radical polymerization catalyst such as peroxides, diazo compounds and the like of which the peroxide catalysts are preferred e.g. di-tert-butyl peroxide, di-tert-amyl peroxide.
• a radical polymerization catalyst such as peroxides, diazo compounds and the like of which the peroxide catalysts are preferred e.g. di-tert-butyl peroxide, di-tert-amyl peroxide.
• curable powder compositions of the present invention is formed by the lower curing temperature, which has to be applied, e.g. 140° C. during 30 minutes instead of the conventional temperature of 175 and higher, in combination with a good flow-out and a good stability.
• the most preferred coating compositions comprise components (bi) and (bii) in an equivalent ratio of from 0.300:1 to 2.800:1.
• curing catalysts can be included in the powder coating compositions in order to reach the desired low temperature curing, i.e. in the temperature range of from 100 to 140° C.
• said curing catalysts are the quaternary ammonium salts, such as tetra(2-4-alkyl)ammonium halide and more in particular e.g. tetrabutylammonium bromide, tetrabutylammoniumchloride, or tin salts of carboxylic acids having from 6-16 carbon atoms, such as tin octoate.
• the reactor is charged with the vinylester of tertiary branched acid monomer and dialkyl ester of ethylenically unsaturated diacid in amounts listed in the table 1 hereinafter, (MMA: methyl methacrylate, DMM: dimethyl maleate, GMA: glycidyl methacrylate) and heated to a temperature to 155° C. under a nitrogen blanket.
• MMA methyl methacrylate
• DMM dimethyl maleate
• GMA glycidyl methacrylate
• the product had the following properties:
• melt viscosity 13 Poise at 175° C. measured with a ICI cone and plate.
• a reactor equipped of a stirrer, a Dean-Stark trap with cooler and a nitrogen inlet was charged with 640.4 grams (3.2 moles) of 1,4 dimethylester cyclohexanedicarboxylate (which is liquid) and 346.44 grams (3.84 moles) of 1,4 butane diol (BDO) At 25° C. the two liquid are not fully miscible. About 1 ml of Ti (isopropoxide) 3 was added to the mixture.
• the reaction mixture is heated to 170° C. in 30 minutes. At this stage the methanol starts to distil. The temperature is raised up to 200° C. when about 220 ml of methanol have been collected. When no more methanol is collected a slight vacuum is applied. After completion of the distillation (about 4 hours), 114,35 grams of 1,4 cyclohexane dicarboxylic acid (a solid) is added. Immediately water started to distil, the temperature is increased to 210-220° C. The end of water distillation was observed after about 4 hours. The low viscous liquid was cooled down to 180° C. and dumped in an aluminium tray. The hot liquid was water like and on cooling starts to be haze and end as white waxy solid.
• the resin could not be ground with a conventional hammer mill and was reduced to small piece by hand and used as such in the formulations.
• the curing agent is a blend of dodecanedioic acid (DDA) and an acid polyester resin made as described above (Di-TMP-1,2 CHDA).
• the acid polyester resin has an acid value of 4635 mmole/kg.
• the molar ratio acid on epoxy groups was for all the formulations equal to 0.78.
• the ratio binder (acrylic resin and acid curing agent)/benzoin (degassing agent) and MODAFLOW powder III (solid flow control agent ex Monsanto) was kept constant and is respectively 1 weight percent for benzoin and 1.5 weight percent the Modaflow.
• the table below gives the exact quantity used for the trials.
• the resins used in the formulations below were coarse ground before use.
• the formulations were placed on a roller bank for at least one hour before extrusion.
• a Buss single screw extruder PLK46 was used. The screw speed was 80 rpm. Temperatures setting considered: 70° C. and 90° C. All the formulations were extruded twice.
• extrudates were then flattened using cooled rolls and fine milled in the jet grinding mill Alpine AFG at 1790 rpm. Powders were additionally sieved using a 300 ⁇ sieve to exclude any granules.
• Powders were applied by electrostatic spraying, using GEMA equipment.
• Formulations A and C were applied easily whereas the other formulations showed a tendency to agglomerate.
• the powder B was agglomerated after one night at room temperature.
• the powders A and C were stable at room temperature.
• the extrudates of Compositions I, II and III resp. have a low through put during the find grinding operation.
• the powders Comp. I, Comp. II and Comp. III were agglomerated at room temperature after 2 hours. These powders were very difficult to spray.
• Cure schedule was 30 minutes at 140° C.
• Polyester Eastman is based on 1,4 CHDA and BDO; the polyester comp. of the invention is based on Di-TMP-1,2 CHDA.
• a: acid resistance test a droplet of sulphuric acid 0.6 N was put on the panel (not covered by a watch glass) for 30, 60 and 90 minutes at a temperature of 50° C.
• Polyester resins were prepared from HHPA: hexahydrophathalic anhydride, TMP: trimethylol propane, DTMP: ditrimethylol propane, DDA: dodecanedoic acid in a 2 1 reactor with nitrogen and a Dean Stark trap.
• the temperature was dropped to 130° C.
• HHPA liquid HHPA
• the intern temperature dropped to 95° C.
• the temperature was risen to 130° C. at the this stage the exothermic reaction starts and the heating was switch off, the maximum intern temperature was 155° C..
• the temperature was kept below 160° C. by external air flow. After 10 minutes the temperature dropped to 150° C. and was maintained at 160° C. for 2 hours before dumping.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Paints Or Removers (AREA)
• Polyesters Or Polycarbonates (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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Citations (13)

• 1998
  • 1998-11-11 BR BR9814408-1A patent/BR9814408A/pt not_active IP Right Cessation
  • 1998-11-11 JP JP2000526560A patent/JP2001527140A/ja active Pending
  • 1998-11-11 US US09/189,571 patent/US6228941B1/en not_active Expired - Fee Related
  • 1998-11-11 CN CN98812657A patent/CN1283205A/zh active Pending
  • 1998-11-11 WO PCT/EP1998/007331 patent/WO1999033889A1/en not_active Application Discontinuation
  • 1998-11-11 EP EP98965160A patent/EP1042379A1/en not_active Withdrawn

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